The present invention relates to vehicle seats and particularly to seat backrests of the type which include internal structures for selectively adjusting the seat cushion contour to provide varying degrees of lumbar support to a seated occupant.
The desirability for providing support for the lumbar region of the back of a seat occupant has long been recognized and various patents, including U.S. Pat. Nos. 3,807,794; 3,890,000; 3,948,558; 3,973,797; 4,155,592; 4,156,544; 4,162,807 and 4,182,533 disclose structures for permitting a fore and aft adjustment of an internal lumbar pad within a back cushion. A co-pending application, Ser. No. 79,861, filed Sept. 28, 1979, and assigned to a common assignee, also discloses such a structure and such disclosure is incorporated by reference herein. U.S. Pat. No. 4,148,522 discloses both fore and aft and vertical adjustment of a lumbar supporter. However, the adjustment is very limited and there are only two vertical positions and three fore and aft positions possible.